physics definition Flashcards
physical quantity
a quantity that is measurable
base quantity
a physical quantity that cannot be derived in terms of other physical quantities
example of base quantity
give 6
length, mass, time, electric current, temperature
scalar quantity
a physical quantity which has ONLY magnitude
vector quantity
a physical quantity which has magnitude and direction
linear motion
motion in a straight line
distance
total length of path of object moving from one location to another
example of scalar quantity
distance, speed
example of vector quantity
displacement, velocity, acceleration
displacement
distance an object moves in a specific direction
Newton’s first law of motion aka as
law of inertia
inertia
every object continues its state of rest or in uniform speed unless acted upon by an external force
momentum
a product of mass and velocity
principle of conservation of momentum
the total momentum of a system is constant, if no external force acts on it
explosion
a closed system which does not involve any external force
what happens to total momentum in an explosion?
it is conserved
force
push or pull
Newton’s second law of motion
net force of an object is proportional to the rate of change of momentum
Newton’s third law of motion
to every action, there is an equal but opposite reaction
impulse
product of force and time interval during which the force acts
impulsive force
rate of change of momentum during collision or explosion
weight
the force of gravity which is exerted on it by Earth
Kepler’s first law (law of ellipses)
orbits of planets are ellipses with the Sun in one of its focus
Kepler’s second law (law of areas)
a line joining the planet with the Sun sweeps over equal areas in equal intervals of time as planet moves in orbit
from kepler’s second law, the planet closer to the Sun
moves faster
kepler’s third law (law of periods)
the square of period is directly proportional to the cube of orbital radius
escape velocity
the minimum velocity an object needs to overcome the gravitational pull of Earth and escape into outer space without falling back
geostationary satellite
a satellite in geostationary orbit around Earth on the equatorial plane
example of man made satellites
ISS Space Station
natural satellite
any object in space orbiting larger planets
thermal equilibrium
a state in which there is no net flow of heat between two bodies
the temperature of the two objects are equal
heat capacity, C
heat which is required to increase the temperature of the substance by 1 C
specific heat capacity, c
heat which is required to increase the temperature of 1 kg of substance by 1 C
latent heat
heat absorbed or given out at a constant temperature during change of phase
latent heat of vaporisation
heat energy released during condensation or boiling
latent heat of fusion
heat energy released during freezing or melting
specific latent heat
amount of heat needed to change phase of 1 kg of substance at a constant temperature
boyle’s law
for a gas of fixed mass, the pressure is inversely proportional to its volume if temperature is constant
pressure law
for a gas of fixed mass, pressure is directly proportional to its absolute temperature if volume is constant
charle’s law
for a gas of fixed mass, the volume of the gas is directly proportional to the absolute temperature of gas provided pressure of gas is constant
how to convert C to K
+ 273
longitudinal wave
wave where the particles of the medium vibrate in a direction that is parallel to direction of wave motion
transverse wave
wave where particles of medium vibrate in direction perpendicular to direction of wave motion
wavefront
a line which vibrations on it are in the same phase
wavelength
distance between two successive wavefront
amplitude
maximum displacement from its equilibrium position
period, T
time taken to complete one oscillation
frequency
number of complete oscillation made by a vibrating system in one second
damping
decrease of amplitude of an oscillating system
during damping, an oscillating system loses its energy to surrounding
usually, the frequency of system remains
unchanged
resonance
happens in forced oscillation
when external force equal to natural frequency of system oscillate with maximum amplitude
reflection
wave strikes an obstacle and undergoes change in direction of propagation
law of reflection states how many things
2
first, angle of incident is
equal to angle of reflection
secondly incident wave, reflected wave and normal lie on
the same plane
refraction
change in direction of propagation when a wave moves from one medium to another
refraction caused by
change of speed of wave moving from one medium to another
water wave refracts towards normal when
it travels from deep to shallow water
water wave refracts away from normal when
it travels from shallow to deep water
light wave refracts towards normal when
propagates to more optically dense medium
light wave refracts away from normal when
propagates to optically less dense medium
diffraction
spreading of wave when it travels through a small obstacle
principle of superposition
when 2 or more waves meet, total displacement at any point is the vector sum ion each individual wave at that point
coherent sources have _____ frequency and amplitude
same
acronym of electromagnetic spectrum
Romeo Made It Very Ugly, X Good
refraction
definition following light and optics
bending of light ray while propagating from one medium to another with different optical density
law of refraction states that
value of sini/sinr is constant for light passing one medium to another
snell’s law
value of sini/sinr is constant for light passing one medium to another
refractive index indicates
the medium’s light bending ability
critical angle, c
angle of incidence in optically denser medium for which angle of refraction is 90
total internal reflection
total reflection of a beam of light at boundary
when angle of incidence in optically denser medium exceeds the critical angle
what are the 2 conditions for Total internal reflection to occur
- light ray must propogate from optically denser medium to less optically dense medium
- angle of incidence must exceed critical angle
power of a lens measure
ability to deviate an incident ray of light
compound microscope
optical instrument used to view very small or fine objects
astronomical telescope
optical instrument used to view objects at a great distance
antinode
a point where 2 crests meet. constructive interference occurs
resultant force
the single force that represents the vector sum of 2 or more forces acting on an object
free body diagram
diagram that shows all forces acting on the object
resolution of forces
process of resolving a force into two components
forces in equilibrium
state an object is in when the forces acting on it produce zero resultant force
triangle of forces
show equilibrium of three forces acting on object
elasticity
property of material that enables object to return to its original shape and size after force acting on it is removed
hooke’s law
extension of spring directly proportional to force applied on spring given the elastic limit is not exceeded
elastic potential energy
energy stored as a result of applying a force to deform an elastic object.
liquid pressure
is the increase in pressure at increasing depths in a liquid.
pressure
continuous physical force exerted on or against an object by something in contact with it.
actual pressure
addition of liquid pressure and atmospheric pressure
atmospheric pressure
pressure within the atmosphere of Earth.
atmospheric pressure aka
barometric pressure
fortin barometer
mercury barometer that measures atmospheric pressure to a high degree of accuracy
function of fortin barometer
measure atmospheric pressure at meteorological centres
function of aneroid barometer
obtain a quick reading of atmospheric pressure
aneroid barometers are suitable to be used in __
homes, ships and aeroplanes
how many units of pressure are there?
4
name the 4 units of pressure
Pa, mm Hg, m H2O, mbar
gas pressure
caused when gas particles hit the walls of their container.
manometer
a device to measure pressures
pascal’s principle
pressure applied on an enclosed fluid is transmitted uniformly in all directions in fluid
hydraulic system
system that uses a liquid to transmit pressure
archimedes principle
an object which is partially or fully immersed in a fluid will experience a buoyant force equal to weight of fluid displaced
buoyant force
force acting upwards on an object immersed in a liquid
what is the one condition for buoyant force to occur
there is pressure difference between lower surface and upper surface of the object
hydrometer
a measuring instrument that measures density of liquids
ballast tanks
a compartment within a ship that holds water, to provide stability for a vessel
plimsoll line
a reference mark indicates the maximum depth the vessel may be safely immersed when loaded with cargo
Bernoulli’s principle
when velocity of a fluid increases, the pressure in fluid decreases and vice versa
lift force
a mechanical force that is produced by the movement of an object through the air.
drag
air resistance that opposes movement
thrust
force produced by jet engines
electric field
region around a charged particle where any electric charge will experience a force
current
rate of flow of charge in a conductor
potential difference
the difference of electrical potential between two points
electric field strength at a given point
electric force acting on a unit positive charge placed at that point
resistance
a measure of the opposition to current flow in an electrical circuit
resistivity
a measure of a conductor’s ability to oppose flow of electric current
non-conductor
a material that x conduct electricity
semiconductor
a material that has an electrical conductivity value between a conductor and an insulator
conductor
a material that conducts electricity
superconductors
a material that conducts electricity w/out resistance
critical temperature
temperature when the resistivity of a superconductor becomes zero
electromotive force
energy per unit electric charge that is imparted by an energy source
voltage drop
decrease of potential difference along the path of a current flowing in an electrical circuit
internal resistance
resistance caused by electrolyte in the dry cell
electrical energy
energy derived as a result of movement of electrons
power
amount of energy transferred
electromagnet
type of magnet in which the magnetic field is produced by an electric current
magnetic field
vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials
catapult field
resultant magnetic field produced by interaction between magnetic field from a current carrying conductor and from a permanent magnet
direct current
one-directional flow of electric charge
electromagnetic induction
production of an electromotive force across an electrical conductor in a changing magnetic field
magnetic flux
magnetic field lines that pass through a surface
alternating current
describes the flow of charge that changes direction periodically
transformer
changes voltage of a.c current
step up transformer
amplifies input voltage
step down transformer
decrease input voltage
ideal transformer
a transformer that does not experience energy loss, efficiency is 100%
eddy currents
loops of electrical current induced within conductors by a changing magnetic field in the conductor
